Attacked by Giant Shrimp"
"Mantis Shrimp Ate My Baby!"
"Stomatopod Sinks Fleet"
"Mantis Shrimp Destroys World; Film at 11
of the National Enquirer, headlines such as the above
are unlikely. Then again, after months of reading the mantis
shrimp forum on Reef Central (which you'd think would
be about mantis shrimp-keeping, not mantis shrimp-extermination),
various posts on other message boards and dealing with customers'
questions while working part-time in a local fish store, I
wouldn't be surprised at all by any of those headlines. In
fact, some of those are fairly tame. Mantis shrimp tend to
get a fairly horrible reputation for all manner of atrocities
(see the headlines above again). While the occasional aquarist
or diver may actually get a split-thumb, I'd argue that someone
was most likely putting their thumb where it didn't belong.
Mantis Meets World!
The most commonly made false accusations include:
- Mantis shrimp can and will kill anything.
- Mantis shrimp can and will kill anything for fun.
- Mantis shrimp can and will kill anything for fun
and nothing else in the tank could've done it (including
At the root of this prejudice against mantis shrimp is the
wrongly held belief that the shrimp, also known as stomatopods,
are evil. Fascinating? Yes. Adept hunters? Certainly. Evil?
Not so much, unless feeding themselves is considered evil.
Stomatopods are guilty of simply doing what they were born
to do; their diet just isn't compatible with what many reefkeepers
encountering them in their tanks are willing to tolerate.
In the same way that each fish has a specific diet it prefers,
so, too, do stomatopods.
Fishes are often grouped into general dietary categories
in order to allow fishkeepers to more easily meet their feeding
requirements. In fact, specific 'formulae' of food are even
distributed by some vendors; one mix of food for sponge-eaters,
another mix for "bug-" eaters and a third for herbivorous
fish. The same generalizations can be made for mantis shrimp,
though the labels would have to be changed a bit; maybe to
read "Formula Smasher" and "Formula Piercer."
Stomatopods generally fall into two broad categories: smashers
and spearers. Smashers have raptorial appendages designed
for cracking open shells of gastropods and crustaceans. Spearers'
raptorial appendages are specialized for snagging fish from
the water column by impaling them.
While the spearers do indeed sound like a menace capable
of making fish disappear, they are also very rarely encountered
in our tanks. Almost without exception, stomatopods that pierce
and eat fish are found in muddy areas of the ocean floor where
they can dig burrows more easily. This makes it very rare
for them to be imported on live rock or with corals.
The much more common hitchhiking smashers are often hitchhikers
on live rock, and are often small species that, in time, can
dramatically down-size a cleaning crew, but they aren't doing
it out of malice. Speaking from my limited experience as a
hobbyist, most accidentally imported smashers tend to feed
mostly on "bugs," whatever the tank is fed (frozen
or flake) and tiny or juvenile snails. While some people choose
to feed their mantis shrimp silversides or even flaked food,
this is not their preferred diet. In the anecdotal adventures
of my own caped stomatopod, he faces off occasionally with
crustaceans of various shapes and sizes. When victorious in
capturing his crabby cohabitants he does feast on their remains,
but these crusty critters are definitely listed below most
snails on his "favorite foods" list. I imagine the
menu of choice varies greatly between species. Very large
smashers are, incidentally, available for sale in the aquarium
trade, "Peacocks" and/or "Clowns" most
notable among them, but these are rare hitchhikers indeed
and, like spearers, are usually special-ordered.
As a final rebuttal to the "Mantis shrimp can and will
kill anything" line, my experience with four smaller
species of stomatopod suggests that the mantis shrimp is more
likely to fear fish than to intimidate them. My experience
includes a Gonodactylus smithii, which is known to
"bluff" with its threat display more often than
many other species of stomatopod. The threat display of many
smashers can be used to spook and scare away other competitors
or perceived threats. It is also shown right before a strike
as well. So, just as in poker, you'll have to learn to read
other tell-tale signs. Of the others, kept more briefly, Haptosquilla
glyptocercus was the most bold. Though it never attacked
fish and typically stayed holed-up when fish were around,
it did seem completely unafraid as it snapped brine shrimp
or mysids from the water column, even directly in front of
the fish. Neogonodactylus wennerae is the most varied
I have seen, with no two individuals looking anything alike
at first glance. I didn't spend enough time with this species
to say much more then they seem to be one of the most commonly
imported and their behavior varies almost as much as their
coloration. Another small unidentified mantis shrimp I've
dealt with may have actually died of fright while acclimating
to the sump. It seemed genuinely terrified by any movement
above or outside its container.
Mantis shrimp scoping out possible prey.
So then, what might we assume from the above? When the stomatopod
is bigger than or stronger than or, in fact, regards itself
to be in any position of overwhelming superiority (such as
when pitted against brine shrimp) the mantis shrimp is likely
to appear to be the most fearsome creature ever seen in a
reef tank. At the same time if the mantis shrimp feels even
slightly under-prepared for the encounter it may display,
but will ultimately run away and hide or, in certain cases,
stay bold for too long and lose an eye.
It's all fun and games until someone loses an eye
"So, enough about fish, I heard they also destroy corals
and even eat the heads off chickens
Smashers are certainly a constructive lot. My own Gonodactylus
smithii was found under the base of a large toadstool
leather. In the weeks leading up to finally taking him home,
I did notice that he would occasionally groom the base of
the leather when it encroached too closely to the entrance
of his cave. In over a year in captivity since then, he has
rearranged several corals, including the occasional chip of
zoanthids or, most recently, half a colony of translucent
cup coral he seems to have some attraction toward (it sounds
like more than it is
half the colony is a branch with
one polyp at the end). In all of those rearrangements he has
never destroyed a coral, and in most cases I suspect that
he cared little for the polyps and was more interested in
the shape or size of the rubble to which they were attached.
I may be underestimating his aesthetic sense, though. Maybe
he was after the rubble with the corals attached because he
wanted to add a little color to his home. More practically,
he could have been trying to better camouflage his home, as
Regarding eating the heads off live chickens, I think that
went out of style in the '80s. Though, just this week, I did
feed a treat of roasted turkey breast to one seemingly happy
"Fine, mantis-lover; then what should I do about it
if I do find one and don't want it?"
First, make sure that's the beast you're hunting. If you've
determined you have a mantis by sound alone, many things can
be misheard as mantis-clicks. Pistol shrimp can, to the untrained
ear, sound very much like a stomatopod smashing away at rock
or snails. After adding a fighting conch to my display, I
spent a week fully convinced I had a mantis; the sound of
the large snail as it encountered the aquarium walls sounded
very much like a mantis. Likewise, any snail may be capable
of making similar noises when traversing the glass walls of
its tiny "captive ocean" home.
Let's assume for a moment that you have a visual ID on your
unwanted (at least in the main display) stomatopod. Many drawings
and descriptions on Reef Central and elsewhere around the
web detail the construction of mantis traps. These traps are
simple and may even help catch other more destructive creatures
from your rockwork (crabs, hermits, fish etc.). Other means
involve removing the rock containing the stomatopod's home
or using freshwater, soda or seltzer water to force the shrimp's
exit from its burrow. While this doesn't sound pleasant it
also shouldn't necessarily be lethal unless you let the mantis
drown in the wastewater.
Whatever course you choose, should you not desire to keep
the wayward stomatopod for yourself, let others know about
it through local reef clubs or in the Mantis Shrimp Forum
on Reef Central. Many "mantis-lovers" are out there
without a mantis to love and would welcome such a guest to
Links of Interest:
Mantis Shrimp Forum
on Reef Central
The Blueboard "Lurkers
Guide to Stomatopods"
Tim's Continuing Adventures
A special thanks to Legendary
Lures for permission to use an image of one of their lures.